A version of 3G (third-generation) W-CDMA (Wideband-Code Division Multiple Access) system is upgraded from Release99 to Release5 and to Release6. As the version is upgraded, new function is added thereto.
In recent years, the system transition from Release99 to Release5 has been expected, and it has been supposed that a new function of Release5, such as a HSDPA (High Speed Downlink Packet Access), is to be put into practice.
However, it is difficult, from the cost standpoint, for a system operator to upgrade all base stations so as to be corresponding to the new function (Release5) at once. Therefore, in the case of upgrading version of a system, the system is normally formed in the state including both a base station which is corresponding to functions of existing Release99 only and a base station which is corresponding to Release5 having a new function. In this case, if a user desired to use an application which is used in the HSDPA, it is more convenient for the user of a portable telephone to connect to only the base station corresponding to Release5.
With respect to the W-CDMA being a traditional art, as an example in which the feature of cells is determined at a mobile station end so as to perform a selection of a cell, there is a system in which cellular cells and Hot-spot cells exist in mixed. In the system, a mobile station has a table which is the same as a scramble code table provided in a base station, and the cell environment is identified according to the scramble code (see Patent Literature 1). Further, there is an example in which neighboring cell information notified from the base station to the mobile station is ranked for detecting and monitoring of cells, and the necessity of detecting and monitoring of cells and contents of service to be provided are included in the ranking (see Patent Literature 2).
Patent Literature 1: Japanese Patent Application Laid-open No. 2005-86374
Patent Literature 2: Japanese Patent Application Laid-open No. 2005-51568